In general cases, reliability of networks is typically provided by way of link backup, i.e., there are a plurality of links between two devices, where one of the links is taken as a main link, and other links are taken as backup links. In normal cases, packets between those two devices are transferred using the main link. When the main link's failure occurs, the service data flow will be switched to one of the backup links to ensure normal operation of services.
With development of Ethernet technologies and increase of network traffic, there are more and more cases in which a Wide Area Network (WAN) uses Ethernet links. In order to increase reliability and stability of networks, an Ethernet link aggregation technology is proposed. Ethernet link aggregation is named as Link Aggregation (LA) for short, by which a plurality of Ethernet physical links are bundled into one logical link so as to increase link bandwidth. Meanwhile, those links bundle together may effectively improve link reliability by dynamic backup between each other. Using the technology of LA to aggregate a plurality of Ethernet links between two devices into one logical link may not only improve bandwidth utilization by load sharing among the plurality of Ethernet links, but also ensure convergence reliability after a single link fails.
Here, the WAN is used to realize interconnections among Local Area Networks (LANs) or Metropolitan Area Networks (MANs) in different areas. Devices in the WAN may include transmission devices such as a router and etc.